As long as we've been launching spy satellites into space, we've been trying to find ways to hide them from the enemy. Now, thanks to the small sat revolution—and a growing amount of space junk—America has a new way to mask its spying in orbit.

One of the emerging trends of the 21st century is the shrinking size of space satellites, and the hope of replacing large spacecraft with constellations of smaller ones flying in lower orbits. It’s no secret that the same pattern holds true for spy satellites. The National Reconnaissance Office (NRO) has not been shy about funding small sat launchers to loft payloads into space—payloads that could hide amid the thousands of objects now in low-Earth orbit.

“The part of my career I don't talk much about was working with the military on small satellites,” says Jim Cantrell, industry veteran and founder of the launch company Vector. “We were trying to work with the military to find out the utility of these very small things, including CubeSats ... one man's space debris is another man's weapons system, right?”

A Mission Cloaked In Secrecy

Public discussions about the military benefits of small satellites usually focus on the launches. CubeSats are indeed cheaper to fly and can be flown with fewer delays, since the space rockets are smaller and can even be shot from air plane.

But the actions and tactics of the orbital spycraft themselves are often left unmentioned, since it’s so sensitive. “Observability of objects in space is not a topic that most people talk very much about, and I really don't want to go into it,” said Cantrell, whose company Vector has current DoD contracts. “Suffice to say there's a great military interest.”

The National Reconnaissance Office, the operator of many of the U.S.'s spy sats, refused to answer any questions about ways to hide small sats in orbit. Officials there did acknowledge that they are interested in all sizes of spacecraft if it helps their jobs, especially if the private sector is developing them anyway.

"One man's space debris is another man's weapons system, right?"

“The NRO uses small satellites today—along with big satellites, medium satellites and CubesSats,” NRO spokeswoman Loretta DeSio told PM in an email. “Physics sometimes demands a bigger satellite to fill mission requirements. However, the mission capability small satellites are able to provide has significantly improved with advances in parts and components, and investment from private industry. We would expect that trend to continue —and we will continue to leverage the opportunities those improvements offer us.”

It’s getting clear, even in these carefully couched terms, that things are going to get spooky in low-Earth orbit.

Hiding In Plain Sight

In 2014, Russia launched a trio of communications satellites. Like any other launch, spent stages and space debris were left behind in space. Air Force Space Command dutifully catalogued them, including a nondescript piece of debris called Object 2014-28E.

Nondescript until it started to move around in space, that is. One thing about orbits; they are supposed to be predictable. When something moves in an unexpected way, the debris is not debris but a spacecraft. And this object was flying close to the spent stages, manoeuvring to get closer.

This fuelled speculation that the object could be a prototype kamikaze-style sat killer. Other less frantic speculation postulated that it could be used to examine other satellites in orbit, either Russia’s or those operated by geopolitical foes. Either way, the lesson was learned.

“It’s not hard to make it look like space debris from the upper stage,” says Todd Harrison, director of the Aerospace Security Project at the think tank CSIS. “That’s the hard part about space situational awareness. You’re not up close, looking at these things with the naked eye. You’re relying on radar reflections and reflections of light from the sun from a certain angle, things like that to deduce what they are.”

Whenever a satellite is launched, government uses radar to track whatever goes into space. The U.S. Air Force maintains the official database of orbital activity, examining the way things in orbit change each time it passes overhead.

“The tricky thing about small satellites when we’re talking about really small ones, nanosats or CubeSat-sized, is that they start to get difficult to track,” says Harrison. “Even in low-Earth orbit, it can be tricky to make sure you’re picking them up and tracking the same object every time is passes through. And it can be difficult to distinguish those small satellites from other pieces of debris that might be floating around.”

Earth’s orbit is getting pretty thick with material, so a small spy sat has plenty of places to hide—and it’s an environment that changes all the time. “The thing about debris is that it can break up on its own,” Harrison says. “There could be a piece from a previous satellite breakup that spontaneously separates into more than one piece and it won’t be clear what happened. Are these new objects?”

Eyes Toward the Skies

Modern tracking radar is supposed to map space junk better than ever before. But small spy sats that will hide in the cloud of space debris may go undetected, even by the most sophisticated new radar or Earth-based electronic signals snooping.

The first of two USAF “Space Fence” installations is being built in Kwajalein Island in the deep Pacific while the other will be built in Australia. Because Kwajalein is so close to the equator, the radar screen it projects is well positioned to catch the overhead traffic. Most satellites in low-Earth orbit pass through the fence multiple times a day.

The space surveillance radar it replaces could track 2,000 pieces of space debris, but the S-band radar of the new Space Fence is expected to detect five to ten times more. “No one knows how much, exactly,” Bruce Schafhauser, Lockheed’s Space Fence program director, told Popular Mechanics earlier this year. “We’ll see how much is up there."

And that’s a problem when it comes to spotting small satellites posing as space junk. With all of those new bits of junk plotted, it will be harder to spot strange activity amid the clutter. The same way that turning on your headlights in a snowstorm obscures visibility, seeing more of the space junk environment may make it harder to see the big picture. Officials at Lockheed Martin, maker of the Space Fence, declined to comment for this story.

And the solution isn't just making our scanning technology even better. Ironically, seeing more space junk may make it harder to spot the small spy satellites lurking among the debris.

“When it comes online it will be able to pick up objects that are much smaller,” Harrison says. “We’re probably going to realize there is more debris out there. That’s good and bad. Picking up smaller things makes it harder to hide, then again, when you are picking up lots of debris that we never had to track before that can make it easier to hide in the noise.”

So What Good Are They?

Not all satellites travel in the same orbits. The NRO’s marquee Key Hole–class spy satellites are in highly elliptical orbits called Geo Transfer Orbits (GTO). These powerful satellites can capture details on the ground with five-inch resolution and pass over every spot on Earth twice a day.

The problem is that these passes are predictable, as orbits tend to be. That gives foes a chance to hide their activities or target the satellite with anti-satellite (ASAT) weapons. Small satellites make harder targets, and since there are many of them, and more easily replaced, they are considered safer from ASAT attacks.

Small satellites don’t offer the coverage that comes with a higher altitude. They are at their best in low-Earth orbit, where their operation requires less power. However, chaining a constellation of small satellites so that they pass overhead at nearly seamless intervals could cover one area of Earth with persistence.

They can also respond to a crisis. In March, DARPA director Steven Walker listed “very capable low-Earth-orbit satellites” as a way to enhance intelligence, surveillance, and reconnaissance when troops are deployed.

To combat a spy sat network could mean developing a rival constellation tasked with hunting their signals.

Small satellites can also make a big difference as data relays. One thing that every CIA analyst and military user of satellite imagery wants is to get data from space in near real-time. Satellites in various orbits, including spy satellites, pass information to each other. Small satellites in a lower orbit could send their data to ones in higher orbits, which have broader lines of sight with receivers on the ground, enabling a speedy delivery.

There’s an interesting role for small satellites that are tasked with signals intelligence missions: they could be ideal for intercepting electronic signals from other satellites.

These snooping satellites would be hard to spot because they would be passive, not moving or manoeuvring but just drifting in formation, hiding amid the space debris. A network of small satellites could act in concert, a synthetic aperture acting as one large antenna to capture RF signals from other satellites .

“They could be networked to provide a capability much greater than what a large satellite could provide,” Harrison says. ”And each one would be difficult to detect and, in theory, could appear to be debris.”

The Tiny Satellite Revolution

Like any other piece of surveillance hardware, there is an opportunity to catch a small spy satellite when it communicates, but there are ways to mask those signals, too. “If you have your small satellites transmit to another satellite, you can use certain parts of the frequency spectrum that the Earth’s atmosphere blocks almost completely, like 60 gigahertz, and so no one could detect that from Earth,” says Harrison.

The relay would obscure the original source of the information, like laundering money through a bank. The signal could then be beamed down within a routine transmission. Of course, a small satellite could intercept such a signal, so to combat a spy sat network could mean developing a rival constellation tasked with hunting their signals.

That conjures up an interesting vision of the future in low-Earth orbit with shadow networks of disguised sats spying on each other. Like any good spy game, it will happen in silence and in secrecy, but in this case the kind that only space can truly provide. We won't know when it starts and we won't know who's winning. In fact, the game may have already begun.